Euan’s Blog – Oxford Clay- a fossil hunters friend

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Tip No. 1 LOOK IN SPOIL HEAPS

The pit at Kings Dyke contains lots of spoil dumps- but mounds of clay which the diggers have piled up while excavating. Looking thoroughly (I hope you like getting muddy, because the best way to look closely is on hands and knees) you’ll find all kinds of interesting bits and bobs in the spoil heaps, such as fish scales, sharks teeth (there are over 15 different sharks recorded from the Oxford clay), bivalves, Ammonite fragments, bits of belemnite guards, and the occasional bone fragment. These will probably have come from a skeleton that was once present, but was distubed during the diggers’ excavating, and bits of the skeleton may have ended up on the spoil heap. Conversely, they may have been preserved as just isolated fragments- perhaps the animal they came from was preyed on and dismembered by predators in the water column, and as they fed, the easily removed bits like the limbs and flippers, sank to the seabed where they were preserved.

Tip No. 2 CHECK- OUT CONCRETIONS

On the pit floor, you’ll see large greyish concretions. Take the time to walk about, and check a few out. They often contain intact fishes and large marine reptile bones. You’ll need a geological hammer, though, as they can be tough to crack.

Tip No. 3 LOOK FOR YELLOW

When bone fragments from Oxford clay are exposed to the elements for a short time (be it a few days or weeks) they gain a sort- of, yellowish tinge.

Keep these tips in mind- I’ve found them useful before, and I’m sure you will. So let’shope we find some good fossils on saturday!:D

 

Oxford Clay- a fosil hunters friend

Posted on July 6, 2014 at 11:20 AM Comments comments (2)

Peterborough is one of the most important Late Jurassic (Callovian to Oxfordian) marine sites in the world, and has provided some of the most complete and well- preserved marine reptile skeletons ever discovered.

Even today, new discoveries are beng made in it, for example, not more than a few years ago, a completely- new genus of Pliosaur was discovered in Kings Dyke. It was named Pachycostasaurus dawni, and was unusual for the high degree of bone ossification in its skeleton, mostly towards the animals front end. The discovery has surprised Palaeontologists, as they didn’t expect a new genus to be found in the Oxford Clay- after all, its the best studied Late Jurassic community. It was suggested that Pachycostasaurus was perhaps a benthic feeder, hunting for bottom- dwelling decapods (crustaceans, like shrimps and lobsters) and molluscs.

 So, on the upcoming visit to Kings Dyke next Saturday, look out for any remains of this animal. For anyone who wants additional information on this animal, search for “A pliosaur (Reptillia, Sauropterygia) exhibiting pachyostosis from the Middle Jurassic of England”published in the journal of the Geological Society. If you do not have access to the journal, try and search for it as a Pdf.

Just to show you how diverse the Oxford Clay reptiles are, here’s a list of some of the known species:

ICHTHYOSAURS
  1. Opthalmosaurus icenicus
PLESIOSAURS
  1. Tricleidus seeleyi
  2. Muraenosaurus leedsi
  3. Muraenosaurus platyclis
  4. Cryptoclidus oxoniensis
  5. 'Picrocleidus beloclis'- now not considered a valid genus and species
PLIOSAURS
  1. Pliosaurus andrewsi
  2. Liopleurodon ferox
  3. Peloneustes philarchus 
  4. Simolestes vorax
  5. Marmornectes candrewsi
  6. Pachycostasaurus dawni
TELEOSAURS
  1. Steneosaurus durobrivensis
  2. Steneosaurus leedsi
  3. Mycterosuchus nasutus

There are also a large number of Metriorynchid Crocodiliformes, including Dakosaurus maximus, Metriorynchus superciliosum, and the newly named Tyrannoneustes. I have not included an exact list for the Metriorynchid and Geosaurid crocodiles because there is currently scientific debate over which specimens should be considered valid species, and exactly how many crocodillian species there were present in the Oxford clay.

So, with so many marine reptiles around, you have a pretty good chance of finding a few bone fragments. Above, are a few tips to help point you in the right direction.

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